Cable alternating current resistance measuring method and device and electronic equipment

Abstract

The invention provides a cable alternating current resistance measuring method and device and electronic equipment, and relates to the technical field of electric power measurement. The method comprises the steps that a current sampling signal and a voltage sampling signal of a cable are obtained, the current sampling signal is obtained by connecting a sampling resistor in series on the secondary side of a current transformer and measuring the voltage drop of the sampling resistor, and the voltage sampling signal is obtained by symmetrically arranging sampling points at the two ends of the cable and synchronously collecting the two ends; converting the current sampling signal and the voltage sampling signal into digital signal flows, wherein the digital signal flows comprise a current signal flow and a voltage signal flow; the digital signal flow is input into a trapezoidal integral resistance calculation model, the alternating current resistance of the cable is obtained, and the trapezoidal integral resistance calculation model is a model which is constructed based on a trapezoidal integral method and used for calculating the alternating current resistance based on the current signal flow and the voltage signal flow in the digital signal flow. According to the invention, the measurement accuracy and flexibility of the cable AC resistance are improved.

Description

Technical Field

[0001] This application relates to the field of power measurement technology, and in particular to a method, apparatus and electronic equipment for measuring the AC resistance of cables. Background Technology

[0002] As a core driving force for modern industrial and social development, the demand for electricity continues to rise with the acceleration of global industrialization and urbanization. Especially in large cities, with increasingly scarce land resources, large-section power cables (typically referring to cables with a cross-sectional area of ​​630 mm² or more) have become an indispensable component of high-voltage transmission networks due to their ability to carry larger currents and achieve efficient power transmission. Therefore, performance evaluation of large-section cables, especially the accurate measurement of their AC resistance, has become an important direction for technological innovation in the power industry.

[0003] Currently, electrical measurement is an effective method for measuring the AC resistance of cables. Its basic principle is to measure the current flowing through the cable conductor and the voltage waveform across the cable sample, and then calculate the AC resistance using the phase angle difference and RMS value of the voltage and current. Among existing technologies, the voltage-current phase difference method is widely used due to its relatively mature research and simple experimental platform construction. This method uses instruments such as oscilloscopes to read voltage and current data, and calculates the AC resistance by comparing the phase difference between the two.

[0004] However, existing methods still suffer from insufficient accuracy and flexibility when measuring the AC resistance of large cross-section cables. Summary of the Invention

[0005] The cable AC resistance measurement method, apparatus, and electronic equipment provided in this application are intended to solve the problem that existing methods still lack sufficient measurement accuracy and flexibility when measuring the AC resistance of large cross-section cables.

[0006] In a first aspect, embodiments of this application provide a method for measuring the AC resistance of a cable, including:

[0007] The current sampling signal and voltage sampling signal of the cable are acquired. The current sampling signal is obtained by connecting a sampling resistor in series on the secondary side of the current transformer and measuring the voltage drop of the sampling resistor. The voltage sampling signal is obtained by symmetrically arranging sampling points at both ends of the cable and performing synchronous acquisition at both ends.

[0008] The current sampling signal and the voltage sampling signal are converted into a digital signal stream, which includes the current signal stream and the voltage signal stream.

[0009] The digital signal stream is input into the trapezoidal integral resistance calculation model to obtain the AC resistance of the cable. The trapezoidal integral resistance calculation model is a model constructed based on the trapezoidal integral method for calculating AC resistance based on the current signal stream and voltage signal stream in the digital signal stream.

[0010] In one possible implementation, the trapezoidal integral resistor calculation model includes a sub-model for calculating the effective value of current.

[0011] The digital signal stream is input into the trapezoidal integrator resistance calculation model to obtain the AC resistance of the cable, including:

[0012] The current signal stream in the digital signal stream is input into the current effective value calculation sub-model to obtain the current effective value. The current effective value calculation sub-model is constructed based on the trapezoidal integral method with current amplitude weighting.

[0013] The active power is determined based on the current signal flow, voltage signal flow, and preset phase compensation coefficient.

[0014] The AC resistance of the cable is determined based on the effective value of the current and the active power.

[0015] In one possible implementation, the trapezoidal integral resistor calculation model further includes a voltage RMS value calculation sub-model; the method also includes:

[0016] The voltage signal stream in the digital signal stream is input into the voltage RMS value calculation sub-model to obtain the voltage RMS value. The voltage RMS value calculation sub-model is constructed based on the trapezoidal integral method with adaptive sampling interval.

[0017] In one possible implementation, converting the current sampling signal and the voltage sampling signal into a digital signal stream includes:

[0018] Based on a preset sampling frequency, the current sampling signal and the voltage sampling signal are sampled to obtain a sequence of sampled values, which includes the current sequence and the voltage sequence.

[0019] Quantize the sequence of sampled values ​​into discrete level values;

[0020] Encode discrete level values ​​into a digital signal stream in binary form.

[0021] In one possible implementation, the method further includes, before converting the current sampling signal and the voltage sampling signal into a digital signal stream:

[0022] The current sampling signal and the voltage sampling signal are input into the amplifier circuit model to obtain the analog current signal and the analog voltage signal. The amplifier circuit model is used to amplify the sampling signal based on the amplification factor.

[0023] Accordingly, the current sampling signal and voltage sampling signal are converted into digital signal streams, including:

[0024] Convert analog current signals and analog voltage signals into digital signal streams.

[0025] In one possible implementation, the current sampling signal and the voltage sampling signal are input to an amplifier circuit model to obtain analog current signals and analog voltage signals, including:

[0026] Determine the input amplitude of the current sampling signal and / or voltage sampling signal;

[0027] Based on the comparison results between the input amplitude and the preset amplitude threshold range, the target amplification factor of the amplifier circuit model is dynamically determined;

[0028] The gain parameters of the amplifier circuit model are adjusted based on the target amplification factor, and the current sampling signal and voltage sampling signal are amplified based on the gain parameters to obtain the analog current signal and analog voltage signal.

[0029] In one possible implementation, the target amplification factor of the amplifier circuit model is dynamically determined based on a comparison between the input amplitude and a preset amplitude threshold range, including:

[0030] If the input amplitude is greater than or equal to the first amplitude threshold, the minimum gain value will be used as the target amplification factor of the amplifier circuit model.

[0031] If the input amplitude is less than or equal to the second amplitude threshold, the maximum gain value will be used as the target amplification factor of the amplifier circuit model.

[0032] If the input amplitude is greater than the second amplitude threshold and less than the first amplitude threshold, then the target amplification factor of the amplifier circuit model is determined based on the input amplitude and the first amplitude threshold.

[0033] In one possible implementation, the value of the sampling resistor is determined based on the equivalent circuit model of the current transformer and a preset maximum current loss error.

[0034] Secondly, embodiments of this application provide a cable AC resistance measuring device, comprising:

[0035] The signal acquisition module is used to acquire the current sampling signal and voltage sampling signal of the cable. The current sampling signal is obtained by connecting a sampling resistor in series on the secondary side of the current transformer and measuring the voltage drop of the sampling resistor. The voltage sampling signal is obtained by symmetrically arranging sampling points at both ends of the cable and performing synchronous acquisition at both ends.

[0036] The analog-to-digital converter module is used to convert current sampling signals and voltage sampling signals into digital signal streams, which include current signal streams and voltage signal streams.

[0037] The resistance calculation module is used to input the digital signal stream into the trapezoidal integral resistance calculation model to obtain the AC resistance of the cable. The trapezoidal integral resistance calculation model is a model built based on the trapezoidal integral method for calculating AC resistance based on the current signal stream and voltage signal stream in the digital signal stream.

[0038] Thirdly, embodiments of this application provide an electronic device, including: a memory and a processor;

[0039] The memory stores the instructions that the computer executes;

[0040] The processor executes computer execution instructions stored in memory, causing the processor to perform the first aspect and / or various possible implementations of the first aspect as described above.

[0041] Fourthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions, which, when executed, are used to implement the first aspect and / or various possible implementations of the first aspect.

[0042] Fifthly, embodiments of this application provide a computer program product, including a computer program that, when executed, implements the first aspect and / or various possible implementations of the first aspect.

[0043] The cable AC resistance measurement method, apparatus, and electronic equipment provided in this application obtain current sampling signals by connecting a sampling resistor in series on the secondary side of a current transformer and measuring its voltage drop. This directly and accurately reflects the current situation in the cable. Simultaneously, by symmetrically arranging sampling points at both ends of the cable and synchronously acquiring voltage signals at both ends, the voltage information at both ends of the cable can be captured more comprehensively, reducing measurement errors caused by cable structure or external interference and improving the accuracy of the sampling signal. Converting the acquired signals into a digital signal stream, utilizing the ease of processing and strong anti-interference capabilities of digital signals, helps to eliminate or reduce the impact of noise and interference on the measurement results. By constructing a trapezoidal integral resistance calculation model based on the trapezoidal integral method, the current and voltage data in the digital signal stream are processed using this model, further improving the accuracy of AC resistance calculation. Furthermore, the trapezoidal integral resistance calculation model can fully utilize the data in the digital signal stream to adapt to different cable characteristics and measurement requirements, thereby improving the flexibility of cable AC resistance measurement. Attached Figure Description

[0044] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0045] Figure 1A schematic diagram of the AC resistance measurement system for cables provided in this application;

[0046] Figure 2 A flowchart illustrating the AC resistance measurement method for cables provided in this application;

[0047] Figure 3 This is a schematic diagram of the structure of the voltage sampling terminal provided in this application;

[0048] Figure 4 A schematic diagram of the specific structure of the AC resistance measurement system for cables provided in this application;

[0049] Figure 5 A schematic diagram showing the results of the AC resistance measurement method for cables provided in this application;

[0050] Figure 6 A schematic diagram of the AC resistance measuring device for cables provided in this application;

[0051] Figure 7 A schematic diagram of the structure of the electronic device provided in this application.

[0052] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0053] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0054] First, let me explain the terms used in this application:

[0055] AC resistance of a cable: refers to the active resistance of a cable that transmits AC power. Its value is greater than that of DC resistance and requires correction through calculation and estimation as well as actual experimental measurement.

[0056] Electrical resistance measurement method: This refers to one of the methods for testing AC resistance. The electrical resistance measurement method measures AC resistance by measuring the current flowing through the cable conductor and the voltage waveform across the cable sample. The AC resistance is then calculated using the phase angle difference and RMS value of the voltage and current.

[0057] Trapezoid method: This is a numerical integration method that divides the integration interval into many small trapezoids and uses the sum of the areas of these small trapezoids to approximate the area under the curve. Compared to the simple rectangular method, it has higher accuracy.

[0058] Large-section cables, due to their high current-carrying capacity, are widely used in urban power grids, industrial power transmission, and long-distance power transmission. However, under long-term high-load operation, these cables are prone to overheating due to insufficient heat dissipation, leading to insulation aging, breakdown, and even fires. For example, in urban underground cable tunnels, the dense laying of cables restricts heat dissipation. If the AC resistance measurement of the cables is inaccurate, problems such as localized overheating or decreased insulation performance may not be detected in time, thus threatening the safety of the power grid. Furthermore, high-voltage transmission systems have extremely high requirements for power transmission efficiency, and the AC resistance of the cables directly affects line losses. By regularly measuring AC resistance, the line loss can be accurately assessed, allowing for timely repair and optimization measures to ensure the stable operation of the power system. Therefore, the performance evaluation of large-section cables, especially the accurate measurement of their AC resistance, has become an important direction for technological innovation in the power industry.

[0059] In existing technologies, electrical measurement is an effective means of measuring the AC resistance of cables. It involves measuring the current flowing through the cable conductor and the voltage waveform across the cable sample, then calculating the AC resistance using the phase angle difference and RMS value of the voltage and current. Currently, the voltage-current phase method for measuring AC resistance uses instruments such as oscilloscopes to read voltage and current data, and calculates the AC resistance by comparing the phase difference between the two. However, due to the multi-layered structure of cables, they often exhibit inductive properties, and the equivalent inductance is only related to the structural dimensions. When AC current flows, the current phase lags behind the voltage phase. These factors result in insufficient accuracy and flexibility in measuring the AC resistance of large-section cables, making it difficult to meet the precise evaluation requirements of large-section cables under complex operating conditions.

[0060] To address the aforementioned issues, this application provides a method, apparatus, and electronic device for measuring the AC resistance of cables. A current sampling signal is obtained by connecting a sampling resistor in series on the secondary side of a current transformer and measuring its voltage drop, thereby improving the accuracy of current measurement. A voltage sampling signal is obtained by symmetrically arranging sampling points at both ends of the cable and performing bipolar synchronous acquisition, which helps reduce measurement errors caused by cable structure or external interference, thus improving the accuracy of voltage measurement. Subsequently, in signal processing, the acquired analog current and voltage signals are converted into digital signal streams. The ease of processing and strong anti-interference capabilities of digital signals facilitate subsequent flexible and accurate calculations. Finally, a trapezoidal integral resistance calculation model based on the trapezoidal integral method is constructed. This model can fully utilize the current and voltage data in the digital signal stream to adapt to different cable characteristics and measurement requirements, achieving the goal of accurately calculating AC resistance while also adding flexibility to the measurement process.

[0061] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0062] The execution subject of the cable AC resistance measurement method provided in this application embodiment can be a computing device such as a server or server cluster. The server can be a mobile phone, computer, tablet, or other device. This application embodiment does not impose any particular limitation on the implementation method of the execution subject, as long as the execution subject can acquire the current sampling signal and voltage sampling signal of the cable. The current sampling signal is obtained by connecting a sampling resistor in series on the secondary side of a current transformer and measuring the voltage drop across the sampling resistor. The voltage sampling signal is obtained by symmetrically arranging sampling points at both ends of the cable and performing synchronous acquisition at both ends. The current and voltage sampling signals are converted into digital signal streams, which include both current and voltage signal streams. The digital signal streams are then input into a trapezoidal integral resistance calculation model to obtain the AC resistance of the cable. The trapezoidal integral resistance calculation model is a model constructed based on the trapezoidal integration method for calculating AC resistance based on the current and voltage signal streams in the digital signal stream.

[0063] In some embodiments, the cable AC resistance measurement method can be applied to a cable AC resistance measurement system to achieve accurate measurement of the cable AC resistance. For example, Figure 1 This is a schematic diagram of the AC resistance measurement system for cables provided in this application, as shown below. Figure 1As shown, the AC resistance measurement system for cables includes a voltage and current sampling model, an analog-to-digital conversion model, and a trapezoidal integral resistance calculation model. Each model performs its own function while working together to complete the task of determining the AC resistance of the cable.

[0064] The voltage and current sampling model is used to acquire the original voltage and current signals at both ends of the cable. Further, the voltage signal across the sampling resistor can be acquired by connecting a current transformer in series with the sampling resistor. The current flowing through the sampling resistor is then determined based on its resistance value, and the cable's current sampling signal is calculated using the transformer ratio. Optionally, the range of values ​​for the sampling resistor can be determined based on a preset current loss error constraint to optimize measurement accuracy.

[0065] In AC circuits, the phase of voltage is constantly changing. If there is a time difference in the sampling of positive and negative voltages, the sampled voltage values ​​will be deviated. The dual-end synchronous sampling method ensures that the sampled voltage signals have the same time reference, providing reliable data support for subsequent accurate calculation of the cable's AC resistance. Therefore, by using two sampling channels with highly consistent performance, the positive and negative voltages at both ends of the cable can be synchronously sampled at the same time. Their spatial symmetry can be used to suppress common-mode and differential-mode interference, and the average value of the voltages at the two sampling points can be calculated to obtain the voltage sampling signal at both ends of the cable.

[0066] Analog-to-digital (ADC) conversion models are used to convert analog signals processed by voltage and current sampling models into digital signal streams, which are then transmitted to subsequent computational units (such as trapezoidal integral resistance calculation models). In practice, the acquired and processed analog signals may contain noise interference, amplitude instability, and other issues. ADC models first preprocess these analog signals, such as using filtering algorithms to remove noise, normalizing the signal amplitude to stabilize it, and possibly supplementing missing parameters. Then, through specific ADC conversion methods, the analog signals are converted into digital signal streams. For example, successive approximation ADC converters complete the conversion by progressively comparing the input analog signal with an internally generated reference voltage. The converted digital signal stream provides the data basis for subsequent resistance calculations.

[0067] In one example, the amplified analog voltage and current signals are sampled at equal intervals at a preset frequency that satisfies the Nyquist sampling theorem; the amplitude of the sampled continuous signal is quantized and mapped to discrete values; the quantized values ​​are encoded into a binary digital signal stream and output to the subsequent computing unit.

[0068] The trapezoidal integral resistance calculation model is used to calculate the AC resistance of a cable using the trapezoidal integral method and the digital signal stream output by the analog-to-digital converter model. As a numerical integration method, the trapezoidal integral divides the cable length into multiple small trapezoidal intervals when calculating the AC resistance. Based on the voltage and current signals in each interval, the trapezoidal integral formula is used to calculate the AC resistance value of the cable.

[0069] In one example, the trapezoidal integral resistance calculation model is based on the voltage and current digital signal streams output by the analog-to-digital conversion model. It uses a trapezoidal integral method combined with adaptive sampling intervals to calculate the effective values ​​of voltage and current respectively. When calculating the effective value of current, a weighting factor is introduced to optimize for higher harmonics. When calculating active power, a phase difference compensation coefficient is introduced to correct small phase deviations between sampling channels. Based on the error characteristics of the trapezoidal integral method, a correction coefficient is introduced to calibrate the final calculation results. Finally, the AC resistance value of the cable is obtained according to the correction coefficient, the effective value of current, and the active power.

[0070] Optionally, the AC resistance measurement system for cables may also include an amplifier circuit model. This amplifier circuit model is used to optimize the weak sampled signal after the voltage and current sampling model completes the original signal acquisition and before the analog-to-digital conversion model performs signal conversion. On the one hand, an appropriate amplification factor can be selected based on the input signal amplitude and subsequent analog-to-digital conversion requirements. Simultaneously, a feedback resistor with high precision and good temperature stability can be selected to adjust the gain of the amplifier circuit and ensure its stability. For example, when the input signal amplitude is small and the input range of the analog-to-digital converter is large, a larger amplification factor is required, and the selection of the feedback resistor will affect the amplification effect and stability. On the other hand, the amplifier circuit model can also perform signal filtering. For example, RC filter circuits, LC filter circuits, and other filtering methods can be used to remove high-frequency noise and interference signals from the signal, making the signal smoother and providing a higher quality signal for the analog-to-digital conversion model.

[0071] In one example, the amplifier circuit model filters the weak voltage and current signals output by the voltage and current sampling model to eliminate high-frequency noise; and dynamically selects and applies an appropriate amplification factor according to the real-time amplitude of the input signal to amplify the signal, so as to ensure that its amplitude and power meet the requirements of subsequent analog-to-digital conversion, while avoiding signal saturation or being too small.

[0072] The cable AC resistance measurement system provided in this application embodiment achieves its accuracy and reliability through the synergistic effect of various models. The voltage and current sampling model accurately acquires the original signal, the amplifier circuit model (if applicable) optimizes the signal processing, the analog-to-digital conversion model converts the analog signal into a digital signal, and finally the trapezoidal integral resistance calculation model calculates the cable AC resistance. This system is applicable to various cable AC resistance measurement scenarios.

[0073] Figure 2 This is a flowchart illustrating the cable AC resistance measurement method provided in this application. The execution entity of this method can be a system server or other server storing the cable AC resistance measurement method (e.g., [example server]). Figure 1 The AC resistance measurement system for cables in this embodiment is not particularly limited here. Figure 2 As shown, the method may include:

[0074] S201. Acquire the current sampling signal and voltage sampling signal of the cable. The current sampling signal is obtained by connecting a sampling resistor in series on the secondary side of the current transformer and measuring the voltage drop of the sampling resistor. The voltage sampling signal is obtained by symmetrically arranging sampling points at both ends of the cable and performing synchronous acquisition at both ends.

[0075] In this system, a current transformer is an instrument that converts a large primary current into a small secondary current for measurement based on the principle of electromagnetic induction. In this step, it acts as a coupling and conversion device for the current signal. The secondary side is the side of the current transformer connected to the measurement circuit, typically outputting a small standard current. A sampling resistor is a resistor that converts the current signal into a voltage signal for measurement and analysis. Its resistance value is usually small and highly accurate, and it is connected in series in the secondary circuit of the current transformer.

[0076] In some examples, the primary winding of a current transformer is connected in series with the circuit of the cable under test; a pre-selected sampling resistor is connected in series with the secondary winding of the current transformer; the alternating current flowing through the cable... A proportionally reduced (due to the turns ratio) current transformer will be induced on the secondary side of the current transformer. (determined) current Current When water flows through the sampling resistor, according to Ohm's law, a voltage equal to or opposite to the input voltage will be generated across its terminals. proportional voltage drop Therefore, by obtaining the voltage across the sampling resistor connected in series in the current transformer circuit; based on this voltage and the resistance value of the sampling resistor, the induced current is determined; and based on the induced current and the transformation ratio of the current transformer, the current sampling signal of the cable can be obtained by reverse calculation.

[0077] For example, if the resistance of the sampling resistor is... The voltage drop across the sampling resistor is The secondary current can then be deduced. Then, based on the transformer ratio, the actual current in the cable (i.e., the current sampling signal) is calculated. .

[0078] It should be noted that the sampling resistor for cable measurement can be determined by current loss constraints; alternatively, different resistance values ​​can be switched during cable measurement using relays or analog switches to accommodate a wide range of current measurements from milliamperes to tens of amperes, achieving higher measurement accuracy. Sampling resistors with low temperature drift coefficients (such as manganin resistors) can also be used, or the sampling resistor can be placed in a constant-temperature environment to reduce the impact of resistance changes caused by temperature rise on measurement accuracy.

[0079] In this context, "both ends of the cable" refers to the two ends of the conductor in the cable under test, i.e., the input and output ends where the AC test signal is applied. Symmetrical sampling point arrangement means setting voltage sampling points at both ends of the cable according to a symmetrical principle to ensure the representativeness and accuracy of the sampling. This means that at each end of the cable, instead of a single lead, voltage sampling wires are arranged in a specific geometrically symmetrical manner. Dual-end synchronous acquisition refers to simultaneously acquiring voltage signals from sampling points at both ends of the cable, ensuring that the acquired data is consistent in time.

[0080] The symmetrical arrangement of sampling points can be adjusted according to the length and structure of the cable. For shorter cables, one sampling point can be placed at each end; for longer cables, multiple symmetrical sampling points can be placed at both ends, and then the average value is taken. Dual-end synchronous acquisition can use a dedicated multi-channel synchronous acquisition card to ensure that multiple channels acquire data simultaneously.

[0081] In some examples, when acquiring voltage sampling signals, sampling points can include multiple points, such as two pairs of sampling points, arranged symmetrically about the cable center with an angle of 180 degrees between adjacent sampling pairs. This is to allow interference signals induced by external electromagnetic interference at the symmetrical sampling points to cancel each other out. Further, at end A of the cable, one (or more) pairs of sampling lines are arranged, these two lines being spatially symmetrical about the cable axis (e.g., at an angle of 180 degrees) and twisted together; at end B of the cable, another pair of symmetrical sampling lines are arranged in the same manner. Optionally, the sampling lines at ends A and B can be connected to the positive and negative input terminals of a differential amplifier, respectively; or connected to other device ports used for voltage signal acquisition. When an alternating current flows through the cable, an interference electromotive force is induced on each individual sampling line due to the alternating magnetic field around it. Due to the symmetrical arrangement, the interference electromotive forces on the two sampling lines at the same end are equal in magnitude and opposite in direction (common-mode interference), which will cancel each other out in subsequent differential measurements. At the same time, the true potential difference (differential-mode signal) between the two ends of the cable conductor can be effectively extracted. By synchronously acquiring the voltages at ends A and B, the true voltage drop (i.e., voltage sampling signal) at both ends of the cable can be accurately calculated.

[0082] S202. Convert the current sampling signal and voltage sampling signal into a digital signal stream, which includes the current signal stream and the voltage signal stream.

[0083] In this step, the digital signal stream can be a series of discrete digital signal sequences obtained by analog-to-digital conversion, which facilitates computer storage, processing, and analysis. The current signal stream and voltage signal stream are digital signal streams converted from current and voltage sampling signals, respectively.

[0084] For example, an analog-to-digital converter (ADC) can be used to convert the acquired analog current and voltage signals into digital signals, which are then arranged in chronological order to form a digital signal stream, including a current signal stream and a voltage signal stream.

[0085] Furthermore, the instantaneous voltage value of the analog signal can be rapidly measured at fixed time intervals (sampling frequency, such as 100 kS / s). According to the Nyquist sampling theorem, the sampling frequency should be at least twice that of the highest frequency component of the signal. Each sampled continuous voltage value is mapped to the nearest discrete level; the number of these levels is determined by the ADC resolution (e.g., 16 bits, i.e., 65536 levels). Each quantized level value is then converted into a corresponding binary digital code. Finally, two digital sequences strictly synchronized with time are obtained, such as voltage signal streams. and current signal flow .

[0086] S203. Input the digital signal stream into the trapezoidal integral resistance calculation model to obtain the AC resistance of the cable. The trapezoidal integral resistance calculation model is a model constructed based on the trapezoidal integral method for calculating AC resistance based on the current signal stream and voltage signal stream in the digital signal stream.

[0087] In this step, the trapezoidal integral resistance calculation model is a mathematical model built based on the trapezoidal integral method. Using the input current and voltage signal flows, the AC resistance of the cable is calculated accordingly. For example, the AC resistance can be indirectly obtained by calculating the effective values ​​of voltage and current, as well as their active power, using the trapezoidal integral method.

[0088] The trapezoidal integral resistance calculation model can be implemented through software programming, such as writing corresponding algorithm programs using programming languages ​​like Python and C++. Alternatively, specialized mathematical calculation software, such as MATLAB, can be used to perform trapezoidal integral calculations using pre-defined numerical calculation functions. For example, in practical applications, the appropriate programming language or software tool can be selected to implement the model based on the actual equipment or software conditions and the user's specific needs.

[0089] Optionally, in addition to the basic trapezoidal integral calculation, the trapezoidal integral resistance calculation model can also be configured to automatically reduce the sampling interval h in regions with drastic signal changes (rich in high-frequency harmonics). kIn regions of gradual change, the interval can be increased to optimize computation while maintaining accuracy. Alternatively, when calculating active power, the voltage and current phase differences caused by sensor and circuit delays can be identified and compensated. For example, software compensation can be performed using Hilbert transform or a pre-stored phase-frequency response table. Alternatively, based on the theoretical error formula of the trapezoidal integral method, the integration error under the current sampling can be estimated, and a correction coefficient λ can be introduced to correct the final calculation result.

[0090] The cable AC resistance measurement method provided in this application, through the specific current and voltage sampling methods described above, can accurately acquire current and voltage data reflecting the actual operating state of the cable, reducing errors that may be caused by traditional sampling methods. The use of digital signal streams further ensures the accuracy of signals during transmission and processing, helping to eliminate or reduce the impact of noise and interference on the measurement results. The trapezoidal integral resistance calculation model, based on precise mathematical methods, performs in-depth analysis of digital signals to obtain more accurate AC resistance values, thereby improving measurement accuracy. Simultaneously, the sampling point arrangement can be flexibly adjusted according to the actual conditions such as the length and specifications of different cables, and the requirement for simultaneous acquisition at both ends can also be achieved through suitable equipment and technology. The digital signal stream processing method makes the measurement data easy to store and transmit, and measurement personnel can choose different times and locations for data analysis and calculation as needed. The trapezoidal integral resistance calculation model is applicable to various types of cable measurements, without being overly limited by special cable parameters or complex operating conditions, thus improving the flexibility of cable AC resistance measurement.

[0091] Based on the above embodiments, the trapezoidal integral resistance calculation model includes a current RMS value calculation sub-model; inputting the digital signal stream into the trapezoidal integral resistance calculation model to obtain the AC resistance of the cable includes: inputting the current signal stream in the digital signal stream into the current RMS value calculation sub-model to obtain the current RMS value, wherein the current RMS value calculation sub-model is constructed based on the current amplitude weighted trapezoidal integral method; determining the active power based on the current signal stream, voltage signal stream, and a preset phase compensation coefficient; and determining the AC resistance of the cable based on the current RMS value and the active power.

[0092] In this embodiment, the current RMS value calculation sub-model can refer to a mathematical model used to calculate the current RMS value. This sub-model is constructed based on the trapezoidal integral method with current amplitude weighting, by calculating the current signal flow (such as...). ) Perform specific integral calculations and weighted processing to obtain the effective value of the current.

[0093] The traditional trapezoidal integral method refers to squaring the instantaneous values ​​at all sampling points (e.g., the square of the instantaneous value at the k-th sampling point) when calculating the effective value. Treating all current amplitudes equally and assigning them the same weight, the trapezoidal integral rule for current amplitude weighting refers to the integration calculation after weighting the current amplitudes based on the traditional trapezoidal integral method. Weighting can assign different weights to currents at different times or in different amplitude ranges according to different needs and current characteristics, to more accurately reflect the overall effect of the current, especially suitable for scenarios with a high proportion of higher harmonics. Therefore, it introduces a weighting factor related to the instantaneous current amplitude (such as the current amplitude weight) during the integration process. The weight can be set based on pre-defined rules or determined based on the current values ​​of two adjacent sampling points. For example, the weight of the kth sampling point is the average of the absolute current values ​​of two adjacent sampling points (such as the k and k-1 sampling points).

[0094] For example, the current RMS value calculation sub-model determines the current RMS value in the following way:

[0095] ;

[0096] in, This is the effective value of the current; The sampling interval (usually a constant); The fundamental period of the signal; The instantaneous current value at the k-th sampling point; is the current amplitude weight of the kth sampling point; n is the total number of sampling intervals within one period.

[0097] In actual cable measurements, the current transformer, voltage sampling circuit, amplifier, or ADC itself introduces a slight signal delay, which may result in a phase difference between the current and voltage digital signal flows that ultimately enter the calculation model (e.g., ...). This phase difference is not a characteristic of the cable itself, but rather an error introduced by the system. The phase compensation coefficient is a parameter introduced to compensate for this phase difference (e.g., ...). By appropriately setting the phase compensation coefficient, the calculated active power can be made more accurate. Active power refers to the integral average value of instantaneous power over a cycle. It reflects the actual power consumed in the circuit. In the measurement of AC resistance of cables, active power is closely related to the phase relationship between current and voltage.

[0098] For example, the active power is determined as follows:

[0099] ;

[0100] in, Active power; The instantaneous voltage value at the k-th sampling point; Let be the instantaneous current value at the kth sampling point.

[0101] Optionally, the inherent phase difference of the system can be measured in a laboratory environment using a standard load and reference instrument at different test frequencies (e.g., 50Hz, 60Hz, 100Hz, 1kHz). And construct a frequency-phase compensation coefficient. The lookup table is used. During actual measurement, the system first analyzes the signal's fundamental frequency, and then looks up the corresponding value in the table. The value is used for active power calculation.

[0102] Furthermore, based on the effective value of the current and the active power, the AC resistance of the cable can be calculated as follows: .

[0103] Optionally, an error correction term can be introduced into the AC resistance calculation to correct the final resistance value, for example, based on the trapezoidal integral error estimate. Introducing a correction factor Calculate the AC resistance of the cable based on the effective value of the current, active power, and correction factor. :

[0104] ;

[0105] ;

[0106] According to numerical analysis theory, the trapezoidal integral method suffers from truncation error, which is proportional to the average value of the second derivative of the signal and the square of the sampling interval. For known major harmonic frequencies... The error of the signal can be theoretically estimated. By introducing a correction coefficient based on the trapezoidal integral theory for secondary calibration, the accuracy of AC resistance measurement can be further improved.

[0107] By introducing a trapezoidal integral method based on current amplitude weighting to calculate the effective value of the current, the accuracy of resistance determination can be improved in scenarios with current waveform distortion and high harmonic content, making the results more consistent with the thermal effect of current. Simultaneously, using a preset phase compensation coefficient to correct for active power can eliminate errors introduced by the inherent phase delay of the system itself. Based on this, the final calculated AC resistance value of the cable can be ensured to have higher accuracy and reliability, solving the measurement error problems caused by current and voltage phase differences and the inaccuracy of traditional calculation methods.

[0108] Based on the above embodiments, the trapezoidal integral resistor calculation model further includes a voltage RMS value calculation sub-model; the method further includes: inputting the voltage signal stream in the digital signal stream to the voltage RMS value calculation sub-model to obtain the voltage RMS value, wherein the voltage RMS value calculation sub-model is constructed based on the trapezoidal integral method with adaptive sampling interval.

[0109] In this embodiment, a voltage RMS value calculation sub-model is used to calculate the voltage RMS value. It is constructed based on the trapezoidal integral method with adaptive sampling interval, which can automatically adjust the sampling interval according to the characteristics of the voltage signal to calculate the voltage RMS value more accurately.

[0110] Traditional trapezoidal integration method: typically uses fixed, equally spaced sampling points, such as... The calculations are performed using a constant sampling interval h. The adaptive sampling interval trapezoidal integral method differs from the traditional trapezoidal integral method in that it dynamically adjusts the sampling time interval based on changes in the voltage signal. When the voltage signal changes rapidly, the sampling interval is shortened to capture more detailed information; when the voltage signal changes slowly, the sampling interval is increased to reduce unnecessary data acquisition and improve computational efficiency.

[0111] For example, the voltage RMS calculation sub-model determines the voltage RMS value in the following way:

[0112] ;

[0113] in, This is the effective value of the voltage; The dynamic sampling interval for the k-th sampling interval; The fundamental period of the signal; This represents the instantaneous voltage value at the k-th sampling point.

[0114] Furthermore, by independently calculating the RMS values ​​of voltage and current, the trapezoidal integral resistor calculation model can verify a basic electrical relationship: Apparent power = RMS voltage × RMS current. With apparent power and active power, the model can calculate the power factor = active power / apparent power. For an ideal purely resistive load, the power factor should be very close to 1. If the calculated power factor is much less than 1, it verifies that there is an error or mistake in the resistance determination process, such as excessive system phase error (e.g., ...). Alternatively, the cable under test may not be purely resistive and may exhibit significant inductive characteristics (e.g., at very high frequencies); or there may be serious errors in the sampling or calculation process.

[0115] By calculating the effective value of the voltage, the measurement process can be effectively monitored and the results verified. This allows the system to provide key built-in criteria for the accuracy and reliability of the entire AC resistance measurement by calculating apparent power and power factor, thereby avoiding the output of unreliable results when there are unknown errors, and ensuring the accuracy and reliability of the AC resistance measurement of the cable.

[0116] Based on the above embodiments, converting the current sampling signal and the voltage sampling signal into a digital signal stream includes: sampling the current sampling signal and the voltage sampling signal based on a preset sampling frequency to obtain a sampling value sequence, the sampling value sequence including a current sequence and a voltage sequence; quantizing the sampling value sequence into discrete level values; and encoding the discrete level values ​​into a digital signal stream in binary form.

[0117] In this step, the sampling frequency refers to the number of times the analog signal is sampled per unit time, usually measured in Hertz (Hz). It determines how many samples of the analog signal are acquired within a specific time period. A higher sampling frequency results in more accurate reproduction of the original analog signal, but also increases the amount of data. The sampled value sequence refers to a series of values ​​arranged in chronological order obtained after sampling the current and voltage signals at a preset sampling frequency. This sequence includes the current sequence (corresponding to the sampled values ​​of the current sampling signal) and the voltage sequence (corresponding to the sampled values ​​of the voltage sampling signal).

[0118] One common sampling method is to sample at fixed time intervals. For example, setting the sampling frequency to 1 kHz means sampling once every 1 millisecond. Alternatively, the sampling interval can be dynamically adjusted based on the signal characteristics or actual needs, which is suitable for scenarios with high requirements for the dynamic characteristics of the signal. For example, when a rapid signal change is detected, the sampling interval is shortened; when a slow signal change is detected, the sampling interval is increased.

[0119] Discrete level values ​​are generated by converting continuous sampled values ​​into a discrete, finite number of level values ​​through a quantization process. Quantization refers to mapping the sampled continuous amplitude values ​​to a finite number of discrete values. One quantization method is to uniformly divide the range of sampled values ​​into several quantization levels. For example, for a voltage sample range of 0-5V, 4-bit uniform quantization can be used, dividing 0-5V into 16 levels, each with a width of 5 / 16V. This quantization method is simple to implement and widely used in general analog-to-digital conversion. Alternatively, based on the probability distribution characteristics of the signal, the quantization levels can be non-uniformly divided to improve the quantization accuracy of small signals. Smaller quantization intervals are used for signal values ​​with a high probability of occurrence, while larger quantization intervals are used for signal values ​​with a low probability of occurrence.

[0120] Encoding refers to the process of converting quantized discrete voltage levels into binary form so that computers or other digital devices can store, process, and transmit this data. For example, a quantized voltage level of 5 is represented as 0101 using 4-bit natural binary encoding. This encoding method is simple, intuitive, and easy to process.

[0121] In some examples, based on a pre-set sampling frequency, sampling devices (such as sample-and-hold circuits in analog-to-digital converters) are used to sample current and voltage signals at regular intervals to obtain a sequence of sampled values ​​containing current and voltage sequences. The continuously changing sampled values ​​are approximated to a finite number of discrete level values ​​according to certain quantization rules. For example, for an 8-bit quantizer, the range of sampled values ​​will be divided into 256 discrete level levels. The quantized discrete level values ​​are converted into binary codes to form a digital signal stream in binary form. For example, the quantized level values ​​are converted into binary numbers according to certain encoding rules (such as natural binary encoding).

[0122] In another example, applied to Figure 1 The analog-to-digital conversion model in the AC resistance measurement system for cables includes a signal sampling module, a quantization module, and an encoding module. Further, the signal sampling module, based on a preset sampling frequency and considering the rate of change of the analog signal, periodically samples the current and voltage sampling signals (i.e., analog signals) at equidistant time intervals to achieve uniform sampling. The quantization module divides the sampled analog signal amplitude according to a set quantization level. Based on the required resolution, different quantization intervals are determined, and the sampled values ​​within each interval are grouped into the corresponding quantization level, discretizing the continuously changing analog amplitude and fully balancing the quantization error with the digital signal representation range to reduce signal distortion caused by quantization. The encoding module uses binary encoding to convert the discrete quantization levels obtained after quantization into a corresponding digital code stream, ultimately outputting a stable and ordered digital signal stream.

[0123] By reasonably setting the sampling frequency and adopting different quantization and encoding methods, signals can be flexibly acquired and processed according to actual needs, improving the accuracy and adaptability of signal conversion and providing a high-quality data foundation for subsequent calculation of cable AC resistance based on digital signal flow.

[0124] Based on the above embodiments, before converting the current sampling signal and voltage sampling signal into a digital signal stream, the method may further include: inputting the current sampling signal and voltage sampling signal into an amplifier circuit model to obtain an analog current signal and an analog voltage signal, wherein the amplifier circuit model is used to amplify the sampling signal based on the amplification factor; correspondingly, converting the current sampling signal and voltage sampling signal into a digital signal stream includes: converting the analog current signal and analog voltage signal into a digital signal stream.

[0125] In this embodiment, the amplifier circuit model refers to the circuit topology and principle that describes how the input current sampling signal and voltage sampling signal are amplified based on a set amplification factor. This model can define the signal transmission path in the circuit, the connection method of amplifying components (such as transistors, operational amplifiers, etc.), and the method for calculating and adjusting the amplification factor.

[0126] Analog current and voltage signals are amplified current and voltage signals after being processed by an amplifier circuit model. They remain continuously changing analog quantities, as opposed to discrete digital signals. Analog signals are continuous in both time and amplitude, and can more realistically reflect the changes in the original physical quantities.

[0127] In addition to amplifying the sampled signal, the amplifier circuit model can also include filtering to remove unnecessary high-frequency noise or power frequency interference from the signal, so as to ensure the purity of the signal and prevent calculation errors caused by noise and aliasing.

[0128] The circuit topology in an amplifier circuit model can be customized according to the specific requirements of signal amplification and filtering, including components such as signal input terminals, amplifying elements, filtering networks, output terminals, and power supplies. Furthermore, based on the circuit topology, the parameter values ​​of each component, including resistors, capacitors, inductors, and transistors, are set. The amplifying elements receive the filtered signal and amplify it according to their gain characteristics.

[0129] For example, an amplifier circuit model can be built using an integrated operational amplifier. This could be achieved using a common inverting or non-inverting amplifier circuit structure. The amplification factor is set by adjusting the ratio of the feedback resistor to the input resistor.

[0130] Another example is the use of transistors (such as bipolar junction transistors) to construct amplifier circuits. For instance, in a common-emitter amplifier circuit, the amplification factor is controlled by adjusting parameters such as the bias resistor and collector resistor. In different application scenarios, appropriate transistors and circuit parameters are selected based on the signal's frequency, amplitude, and other characteristics.

[0131] In this approach, a fixed amplification factor can be pre-set based on the expected amplitude range of the cable signal and the requirements of subsequent digital signal processing. For example, in some industrial measurement scenarios where the signal amplitude variation range is relatively stable, a fixed amplification factor can be used to simplify circuit design and debugging.

[0132] The amplification factor can also be dynamically adjusted by introducing components such as variable resistors (e.g., potentiometers) or digital potentiometers. Variable amplification is more suitable for applications requiring adaptation to different signal amplitudes or real-time adjustment of measurement accuracy.

[0133] Furthermore, the current and voltage sampling signals are input to an amplifier circuit model. This model amplifies these signals based on a predetermined amplification factor and simultaneously performs filtering to obtain processed, high-quality analog current and voltage signals. Subsequently, these two optimized analog signals are input to an analog-to-digital converter (ADC) to be converted into digital signal streams. For example, the signal sampling module in the ADC model periodically samples the analog signal parameters of the amplifier circuit model according to a preset sampling frequency, taking into account the rate of change of the analog signal, with the time intervals remaining equidistant to achieve uniform sampling.

[0134] By introducing an amplifier circuit model, the weak and easily interfered sampling signal is boosted and conditioned into a standardized analog signal with moderate amplitude and high signal-to-noise ratio, thereby ensuring that the subsequent analog-to-digital conversion process can be carried out within the optimal dynamic range. This fundamentally reduces the impact of quantization error and noise interference on the measurement results, making the subsequently determined resistor more accurate and reliable.

[0135] Based on the above embodiments, the method for inputting current sampling signals and voltage sampling signals into an amplifier circuit model to obtain analog current signals and analog voltage signals may include: determining the input amplitude of the current sampling signals and / or voltage sampling signals; dynamically determining the target amplification factor of the amplifier circuit model based on the comparison result between the input amplitude and a preset amplitude threshold range; adjusting the gain parameter of the amplifier circuit model based on the target amplification factor; and amplifying the current sampling signals and voltage sampling signals based on the gain parameter to obtain analog current signals and analog voltage signals.

[0136] In this embodiment, the input amplitude can refer to the strength of the current sampling signal and / or voltage sampling signal at a certain moment. It can be the peak value, effective value (RMS), or average value after rectification of the signal, reflecting the amount of energy carried by the signal and is an important indicator for measuring the strength of the signal.

[0137] In one example, an analog peak detection circuit can be used to measure the amplitude of a signal. For instance, a peak detection circuit consisting of diodes and capacitors can quickly detect the peak amplitude of a signal and hold it for a period of time for subsequent measurement and processing.

[0138] The amplitude threshold range can be a pre-defined interval of signal amplitude. This range can be determined based on factors such as the signal processing requirements of subsequent circuits, the accuracy of digital signal conversion, and the overall performance of the system. When the amplitude of the input signal is within this range, the system can be guaranteed to operate normally and accurately.

[0139] The target amplification factor refers to the amplification factor that the amplifier circuit model needs to amplify the input signal by, based on the comparison between the input amplitude and the amplitude threshold range. Its selection is a real-time, automatic process dependent on the current signal conditions. The goal is to ensure that the amplified signal amplitude meets the requirements of subsequent processing, making the amplitude of the final output analog current and / or voltage signal as close as possible to the full-scale range of the ADC, but not exceeding it, thereby maximizing the ADC's utilization and measurement accuracy. In one example, a target amplification factor table is pre-defined based on the relationship between different input amplitudes and amplitude threshold ranges. In practical applications, the target amplification factor is quickly determined by looking up the table based on the measured input amplitude. Alternatively, a specific algorithm can be used to calculate the target amplification factor in real time based on the comparison between the input amplitude and the amplitude threshold range. For example, a proportional-integral-derivative (PID) algorithm can be used to dynamically adjust the target amplification factor based on the deviation between the input amplitude and the amplitude threshold range, making the amplified signal amplitude more stable and accurate.

[0140] Gain parameter, in an amplifier circuit, refers to the parameter used to control the degree of signal amplification. The magnitude of the gain parameter directly determines the amplification factor of the input signal by the amplifier circuit, and adjusting the gain parameter can change the amplitude of the output signal of the amplifier circuit.

[0141] In some embodiments, the gain parameter can be adjusted by changing the resistance value of a variable resistor (such as a potentiometer). For example, in an amplifier circuit composed of operational amplifiers, adjusting the value of the feedback resistor can change the gain of the amplifier circuit. For amplifier circuits with digital control functions, the gain parameter can be controlled by digital signals. For example, using a digital potentiometer or an integrated circuit with digital gain control, the gain of the amplifier circuit can be adjusted by sending corresponding digital instructions through a microcontroller.

[0142] By dynamically determining the target amplification factor and adjusting the gain parameters, the operating state of the amplifier circuit can be automatically optimized according to the actual amplitude of the input signal, so that the amplified signal amplitude is always kept within a suitable range. This effectively avoids the problems of low signal-to-noise ratio caused by too small a signal and saturation distortion caused by too large a signal, improves the accuracy and stability of signal processing, and thus enhances the adaptability and reliability of the entire cable AC resistance measurement method.

[0143] Based on the above embodiments, the target amplification factor of the amplifier circuit model is dynamically determined based on the comparison result between the input amplitude and the preset amplitude threshold range, including: if the input amplitude is greater than or equal to the first amplitude threshold, the minimum gain value is taken as the target amplification factor of the amplifier circuit model; if the input amplitude is less than or equal to the second amplitude threshold, the maximum gain value is taken as the target amplification factor of the amplifier circuit model; if the input amplitude is greater than the second amplitude threshold and less than the first amplitude threshold, the target amplification factor of the amplifier circuit model is determined based on the input amplitude and the first amplitude threshold.

[0144] In this embodiment, the first amplitude threshold is the upper limit of a preset amplitude threshold range. When the amplitude of the input signal reaches or exceeds this value, in order to avoid saturation distortion during the amplification process (i.e., the signal amplitude exceeds the maximum output capability of the amplifier circuit, resulting in clipping of the signal waveform), the amplification factor of the amplifier circuit needs to be set to the minimum gain value.

[0145] The second amplitude threshold is the lower limit of the preset amplitude threshold range. When the amplitude of the input signal is lower than or equal to this value, in order to improve the signal strength and enable the signal to achieve a sufficient signal-to-noise ratio in subsequent processing, the amplification factor of the amplifier circuit needs to be set to the maximum gain value.

[0146] The minimum gain value refers to the minimum amplification factor that an amplifier circuit can be set to. It is usually a limit value set to prevent signal saturation, at which point the amplifier circuit amplifies the signal to the minimum. The maximum gain value corresponds to the maximum amplification factor that an amplifier circuit can be set to. It is used to amplify the signal strength as much as possible when the input signal amplitude is small, in order to meet the requirements of subsequent signal processing.

[0147] The first and second amplitude thresholds can be determined in the following ways: First, based on design experience and actual test results from similar systems, the first and second amplitude thresholds can be set. For example, in a cable signal measurement system, extensive experiments have shown that saturation distortion easily occurs when the input signal amplitude exceeds 5V, and the signal-to-noise ratio is too low below 0.5V. Therefore, the first amplitude threshold can be set to 5V, and the second amplitude threshold to 0.5V. Alternatively, the first and second amplitude thresholds can be determined through theoretical calculations based on the performance parameters of the amplifier circuit, the requirements of subsequent digital signal processing, and the characteristics of the signal itself. For instance, appropriate thresholds can be calculated based on parameters such as the maximum output voltage of the amplifier circuit and the input range of the digital signal converter.

[0148] When the input amplitude is greater than the second amplitude threshold and less than the first amplitude threshold, the target amplification factor can be determined in the following ways: (1) Linear interpolation method: Assume that when the input amplitude is equal to the second amplitude threshold, the amplification factor is the maximum gain value; when the input amplitude is equal to the first amplitude threshold, the amplification factor is the minimum gain value. Then, between the two, the target amplification factor can be determined by linear interpolation based on the ratio between the input amplitude and the second amplitude threshold. For example, if the maximum gain value is 10 and the minimum gain value is 1, when the input amplitude is between the second amplitude threshold and the first amplitude threshold, the target amplification factor can be (10+1) / 2=5.5. (2) Nonlinear adjustment method: According to the characteristics of the signal and the requirements of the system, a nonlinear adjustment method is adopted. For example, for some systems that are sensitive to small signal changes, the amplification factor can be relatively large when the input amplitude is close to the second amplitude threshold; as the input amplitude approaches the first amplitude threshold, the rate of decrease of the amplification factor can be accelerated.

[0149] In some embodiments, the system monitors the input amplitude of the input signal in real time. .when The first amplitude threshold corresponding to the maximum output signal (such as the input voltage threshold corresponding to the maximum output signal) is reached or exceeded. At this point, the input signal no longer needs amplification, and the minimum gain value is used. To avoid amplifier output saturation; when Below the second amplitude threshold (such as the minimum input signal voltage threshold under effective processing). Even when using the maximum gain value The output signal may also be too small to be accurately measured by the ADC; in this case, it is directly locked at the maximum gain. When in the intermediate state, an adjustment coefficient is used. Use the floor function to select the magnification factor. Typically, a value of 0.8 to 0.9 is chosen to prevent momentary output saturation due to minute signal fluctuations. Therefore, the target amplification factor is selected. It can be:

[0150] ;

[0151] Here, `round` is the floor function, ensuring that the processed signal remains discrete. For example, when the reference voltage of the analog-to-digital converter (ADC) is... At that time, the target magnification factor It is necessary to ensure the output signal satisfy: .

[0152] Furthermore, when the amplifier circuit model is a commonly used non-inverting amplifier structure, its amplification factor... It can be determined by the input resistance and feedback resistor Decide( The feedback resistor can be obtained by reverse calculation. Based on the above formula for target magnification, we can obtain:

[0153] .

[0154] By clarifying the method for determining the target amplification factor under different input amplitudes, the amplifier circuit can more accurately adjust the amplification factor according to the actual amplitude of the input signal, further optimizing the signal amplification process, effectively ensuring that the amplitude of the amplified signal is always within the optimal processing range, and improving the signal quality and the accuracy of subsequent measurements.

[0155] Based on the above embodiments, the resistance value of the sampling resistor is determined based on the equivalent circuit model of the current transformer and the preset maximum current loss error.

[0156] In this embodiment, the equivalent circuit model of the current transformer is an abstract representation of its electrical characteristics. It simplifies the complex internal structure and electromagnetic characteristics of the current transformer into a circuit model composed of components such as resistors, inductors, and capacitors. This model allows for easier analysis of the current transformer's performance under different operating conditions, such as current-to-voltage conversion relationships and phase errors.

[0157] The preset maximum current loss error is a maximum allowable range of current loss error pre-set based on factors such as the accuracy requirements of the measurement system and the actual application scenario, before determining the resistance value of the sampling resistor. Current will generate power loss in the sampling resistor; excessive loss will affect the accuracy of the measurement and the efficiency of the system, therefore it needs to be controlled within a certain range.

[0158] In some embodiments, the range of values ​​for the sampling resistor is determined based on current loss constraints; wherein, the current loss constraints are constructed based on the self-inductance of the current transformer, the resistance value of the sampling resistor, the estimated value of the main circuit resistance of the cable under test, and the turns ratio of the current transformer.

[0159] For example, by using the current loss constraint, the selection range of the sampling resistor value can be initially determined as follows: in the circuit power supply Below, the estimated resistance value of the main circuit is... Then the ideal current The calculation formula is as follows:

[0160] ;

[0161] However, current transformers have self-inductance. Including this inductance in the main circuit calculation along with the sampling resistor will affect the current measurement value corresponding to the current transformer. The formula is:

[0162] ;

[0163] in, For mutual inductance; The ratio of the primary and secondary sides of the current transformer.

[0164] It can be based on the current loss requirement and the current loss error. Not exceeding the preset maximum current loss error The initial selection range for the sampling resistor value is determined. The formula for calculating current loss can be:

[0165] ;

[0166] The formula for calculating its constraints is as follows;

[0167] ;

[0168] After simplification, the selected range of sampling resistor values ​​can be expressed using the acquired parameters:

[0169] .

[0170] The value of the sampling resistor is determined by using an equivalent circuit model based on the current transformer and a preset maximum current loss error. This makes the selection of the sampling resistor more scientific and reasonable, effectively reducing current loss error, improving the accuracy of current sampling and the overall precision of the measurement system, while ensuring the stability and reliability of the measurement system, and enhancing the practicality and adaptability of the AC resistance measurement method for cables.

[0171] Figure 3 A schematic diagram of the voltage sampling terminal provided in this application is shown below. Figure 3 As shown, a sampling point is taken at each end of the cable, with a length L between the two points. Symmetrical electrodes are used to synchronously acquire the voltage signal. The reverse cancellation characteristic of the electromotive force induced by the alternating current in the cable in the sampling line is utilized to suppress differential-mode signal interference. The principle is as follows:

[0172] When the cable carries alternating current When this occurs, an alternating magnetic field is generated in the surrounding space, and the magnetic induction intensity at a distance r from the cable's axis increases. During the test, the sampling line was parallel to the cable axis, and the distance between the sampling line and the cable axis was... And the thickness of the cable insulation layer is The magnetic flux passing through the sampling line The induced electromotive force of a single sampling line is derived according to Faraday's law of electromagnetic induction. After sorting, the amplitude of the induced electromotive force of a single sampling line is obtained. If two sampling lines of equal length and arranged in opposite directions are used, the induced electromotive force (EMF) in the two lines will be equal in magnitude, but because they are arranged in opposite directions, the EMF will be in opposite directions. The total induced EMF of the two sampling lines will be different. .

[0173] To effectively suppress interference, sampling lines are evenly distributed around the cable. In dual-stage sampling, two pairs of sampling points are arranged symmetrically about the cable center, with an angle of 180˚ between adjacent pairs. This arrangement ensures the two pairs of sampling lines are perfectly symmetrical on the circumference. When alternating electromagnetic interference exists outside the cable, due to the symmetrical distribution of the sampling points, the differential-mode interference signals induced by each pair of sampling points are equal in magnitude and opposite in direction. Therefore, in subsequent differential measurements, these two interference signals cancel each other out, effectively eliminating the common-mode to differential-mode error caused by the non-coaxiality of the sampling lines and the cable. Dual-stage sampling suppresses electromagnetic interference through a symmetrical point layout, ensuring the accuracy of the measurement results. At this point, the acquired voltage sampling signals at both ends can be used as... and Since the differential mode signal has been suppressed during the sampling process, the average value is taken to obtain the voltage sampling signal of the AC voltage at both ends of the large cross-section cable. .

[0174] Figure 4 This is a schematic diagram of the specific structure of the AC resistance measurement system for cables provided in this application. Figure 4 As shown, a current sensor is connected in series with a sampling resistor (omitted here, which can be deployed between the current sensor and the analog-to-digital converter) and then connected to the main circuit of the cable to be measured (including the power generation device, cable conductor, and resistance, etc.). The two ends of the large-section cable (end A and end B) are connected to the measurement circuit after being twisted together with wires. Both ends are then connected to the analog-to-digital converter (ADC) after passing through an amplification circuit (omitted here, which can be a conventional amplification circuit deployed between the current sensor and the analog-to-digital converter, and between the ends of the large-section cable after being twisted together with wires and the analog-to-digital converter). Finally, the data is connected to the data processing unit.

[0175] based on Figure 4 The embodiment of the cable AC resistance measurement system, in this embodiment... Figure 1 , Figure 2 and Figure 3Based on the embodiments, the method for measuring the AC resistance of cables is described in detail. The method includes: (1) applying a non-sinusoidal signal current (such as...) to the conductor of the cable to be tested. Figure 4 The return current (current in the circuit) is maintained for a certain period of time. For example, the cable conductor under test is placed in an indoor environment during the test, and the length of the cable conductor under test should be no less than 3.5m and the cross-sectional area should be no less than 400mm². 2 , and the current is greater than 100A. (2) Under stable conditions, obtain the voltage and current at both ends of the conductor of the large cross-section cable to be tested. Among them, the current signal acquisition method includes: the current transformer is connected in series with a resistor, which passes through the closed loop formed by the conductor of the cable to be tested, so as to measure the current value of the closed loop. The voltage signal acquisition method includes: several wires are connected to both ends of the conductor of the cable to be tested, and twisted in the middle of the cable, so as to measure the average voltage at both ends of the cable conductor. (3) Repeat step (2) according to the preset number of rounds and preset time, and obtain the AC resistance by trapezoidal integration of the voltage and current obtained in different rounds, and calculate the average value of AC resistance according to the AC resistance value. For example, the preset number of rounds is not less than 10 times, and the preset time is not less than 1 hour.

[0176] To further explain the effects of the embodiments of this application, the following examples are provided in conjunction with experimental data.

[0177] (1) Experimental procedure: To ensure the rationality of the sampling resistor and voltage amplification factor, a preliminary experiment was conducted before the formal experiment:

[0178] ①According to the formula Preliminary estimate of sampling resistance The theoretical scope.

[0179] Standard resistors of different values ​​(0.005Ω, 0.01Ω, and 0.02Ω) were connected in series with the secondary coil of the current transformer. With a non-sinusoidal current of 100A flowing through the cable, the secondary circuit current and the voltage across the sampling resistor were measured. The deviation between the theoretically calculated values ​​and the actual measured values ​​was compared, and the resistor with the smallest deviation (error <1%) and power loss not exceeding the rated capacity of the transformer was selected as the final sampling resistor. The test results confirmed that the 0.01Ω resistor met the requirements.

[0180] ② Without connecting the amplifier circuit, directly measure the amplitude of the original voltage signal output from the twisted wires at both ends of the cable. Based on the measured maximum and minimum voltage values, and combined with the ADC input range, use the formula... To determine the required amplification factor, the output signal saturation was tested at different gain levels (×10, ×50, ×100) to ultimately determine the dynamic gain range and set it. , as well as As an adaptive adjustment parameter.

[0181] (2) Formal test procedure: ① Connect the current transformer in series with the 0.01Ω sampling resistor determined in the pre-experiment and then power the device at a frequency of 50 Hz. ② Apply a non-sinusoidal current signal to the test cable, with each segment of current applied for 1.5 hours. ③ Repeat step ② 10 times, extracting the voltage and current signals measured by the current transformer each time. ④ Process the converted voltage and current signals into a digital signal stream using analog-to-digital conversion and computer software. ⑤ Calculate the AC resistance of the test cable conductor and its waveform according to the AC resistance calculation formula provided by this invention, as shown below. Figure 5 As shown in the figure, the waveform with a maximum value of 0.08791V is a voltage wave, and the waveform with a maximum value of 1072A is a current wave.

[0182] The cable AC resistance measurement method provided in this application provides an accurate sampling and testing method for measuring cable AC resistance based on electrical measurement. This method effectively samples voltage and current signals, suppresses differential-mode signals, and calculates the cable's AC resistance using trapezoidal integrals. This facilitates better measurement of the AC resistance of cables with large cross-sections, leading to better evaluation of power transmission efficiency and equipment performance. Furthermore, traditional voltage sampling models only measure the voltage signals at both ends of the cable, failing to adequately represent the intermediate voltage signal. The voltage sampling model in this application, by sampling the voltage signal after the conductors at both ends of the cable are twisted together, better represents the intermediate voltage signal, reducing sampling errors. The trapezoidal integral calculation model for calculating the AC resistance of large cross-section cables improves calculation accuracy and efficiency, and is highly adaptable. Through piecewise linearization, it can also be applied to other signal modes such as nonlinear functions.

[0183] The AC resistance of large-section cables obtained in this way helps to accurately assess power loss, thereby optimizing power transmission efficiency, reducing energy waste, and helping to detect potential faults in large-section cables in a timely manner.

[0184] Figure 6 A schematic diagram of the cable AC resistance measuring device provided in this application is shown below. Figure 6 As shown, the cable AC resistance measuring device 60 provided in this embodiment includes:

[0185] The signal acquisition module 601 is used to acquire the current sampling signal and voltage sampling signal of the cable. The current sampling signal is obtained by connecting a sampling resistor in series on the secondary side of the current transformer and measuring the voltage drop of the sampling resistor. The voltage sampling signal is obtained by symmetrically arranging sampling points at both ends of the cable and performing bipolar synchronous acquisition.

[0186] The analog-to-digital converter module 602 is used to convert current sampling signals and voltage sampling signals into digital signal streams, which include current signal streams and voltage signal streams.

[0187] The resistance calculation module 603 is used to input the digital signal stream into the trapezoidal integral resistance calculation model to obtain the AC resistance of the cable. The trapezoidal integral resistance calculation model is a model constructed based on the trapezoidal integral method for calculating AC resistance based on the voltage and current in the digital signal stream.

[0188] In one possible implementation, the resistance calculation module 603 can also be used to: input the current signal flow in the digital signal flow to the current effective value calculation sub-model to obtain the current effective value, wherein the current effective value calculation sub-model is constructed based on the trapezoidal integral method of current amplitude weighting; determine the active power based on the current signal flow, voltage signal flow, and preset phase compensation coefficient; and determine the AC resistance of the cable based on the current effective value and active power.

[0189] In one possible implementation, the resistance calculation module 603 can also be used to: input the voltage signal stream in the digital signal stream to the voltage RMS value calculation sub-model to obtain the voltage RMS value, wherein the voltage RMS value calculation sub-model is constructed based on the trapezoidal integral method with adaptive sampling interval.

[0190] In one possible implementation, the analog-to-digital converter module 602 can also be used to: sample the current sampling signal and the voltage sampling signal based on a preset sampling frequency to obtain a sampled value sequence, the sampled value sequence including the current sequence and the voltage sequence; and quantize the sampled value sequence into discrete level values.

[0191] Encode discrete level values ​​into a digital signal stream in binary form.

[0192] In one possible implementation, the analog-to-digital conversion module 602 can also be used to: input the current sampling signal and the voltage sampling signal to the amplifier circuit model to obtain the analog current signal and the analog voltage signal, wherein the amplifier circuit model is used to amplify the sampling signal based on the amplification factor; and convert the analog current signal and the analog voltage signal into a digital signal stream.

[0193] In one possible implementation, the analog-to-digital conversion module 602 can also be used to: determine the input amplitude of the current sampling signal and / or the voltage sampling signal; dynamically determine the target amplification factor of the amplifier circuit model based on the comparison result of the input amplitude and a preset amplitude threshold range; adjust the gain parameter of the amplifier circuit model based on the target amplification factor; and amplify the current sampling signal and the voltage sampling signal based on the gain parameter to obtain the analog current signal and the analog voltage signal.

[0194] In one possible implementation, the analog-to-digital conversion module 602 can also be used to: if the input amplitude is greater than or equal to a first amplitude threshold, use the minimum gain value as the target amplification factor of the amplifier circuit model; if the input amplitude is less than or equal to a second amplitude threshold, use the maximum gain value as the target amplification factor of the amplifier circuit model; if the input amplitude is greater than the second amplitude threshold and less than the first amplitude threshold, determine the target amplification factor of the amplifier circuit model based on the input amplitude and the first amplitude threshold.

[0195] The cable AC resistance measuring device provided in this embodiment can perform the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.

[0196] Figure 7 A schematic diagram of the structure of the electronic device provided in this application. Figure 7 As shown, the electronic device 70 provided in this embodiment includes at least one processor 701 and a memory 702. Optionally, the device 70 further includes a communication component 703. The processor 701, memory 702, and communication component 703 are connected via a bus 704.

[0197] In a specific implementation, at least one processor 701 executes computer execution instructions stored in memory 702, causing at least one processor 701 to perform the above-described method.

[0198] The specific implementation process of processor 701 can be found in the above method embodiments, and its implementation principle and technical effect are similar. It will not be repeated here.

[0199] In the above embodiments, it should be understood that the processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor.

[0200] The memory may include random access memory (RAM) and may also include non-volatile memory (NVM), such as at least one disk storage device.

[0201] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, the buses shown in the accompanying drawings are not limited to a single bus or a single type of bus.

[0202] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.

[0203] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method.

[0204] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0205] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and the readable storage medium can exist as discrete components in the device.

[0206] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0207] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0208] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0209] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0210] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0211] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method of measuring the AC resistance of a cable, characterized by, The method comprises: obtaining a current sampling signal and a voltage sampling signal of a cable, wherein the current sampling signal is obtained by connecting a sampling resistor in series at a secondary side of a current transformer and measuring a voltage drop of the sampling resistor, and the voltage sampling signal is obtained by symmetrically arranging sampling points at both ends of the cable and performing double-end synchronous sampling; converting the current sampling signal and the voltage sampling signal into a digital signal stream, the digital signal stream comprising a current signal stream and a voltage signal stream; inputting the digital signal stream into a trapezoidal integral resistance calculation model to obtain an alternating current resistance of the cable, wherein the trapezoidal integral resistance calculation model is a model for calculating an alternating current resistance based on a current signal stream and a voltage signal stream in a digital signal stream, and the model is constructed based on a trapezoidal integral method.

2. The method of claim 1, wherein, The trapezoidal integral resistance calculation model comprises a current effective value calculation sub-model. The inputting the digital signal stream into the trapezoidal integral resistance calculation model to obtain the alternating current resistance of the cable comprises: inputting the current signal stream in the digital signal stream into the current effective value calculation sub-model to obtain a current effective value, wherein the current effective value calculation sub-model is constructed based on a current amplitude weighted trapezoidal integral method; determining an active power based on the current signal stream, the voltage signal stream, and a preset phase compensation coefficient; determining the alternating current resistance of the cable based on the current effective value and the active power.

3. The method of claim 2, wherein, The trapezoidal integral resistance calculation model further comprises a voltage effective value calculation sub-model, and the method further comprises: inputting the voltage signal stream in the digital signal stream into the voltage effective value calculation sub-model to obtain a voltage effective value, wherein the voltage effective value calculation sub-model is constructed based on an adaptive sampling interval trapezoidal integral method.

4. The method of claim 1, wherein, The converting the current sampling signal and the voltage sampling signal into a digital signal stream comprises: sampling the current sampling signal and the voltage sampling signal based on a preset sampling frequency to obtain a sampling value sequence, the sampling value sequence comprising a current sequence and a voltage sequence; quantizing the sampling value sequence into discrete level values; encoding the discrete level values into a digital signal stream in binary form.

5. The method according to any one of claims 1-4, characterized in that, Before the converting the current sampling signal and the voltage sampling signal into a digital signal stream, the method further comprises: inputting the current sampling signal and the voltage sampling signal into an amplification circuit model to obtain an analog current signal and an analog voltage signal, wherein the amplification circuit model is used for amplifying a sampling signal based on an amplification multiple; correspondingly, the converting the current sampling signal and the voltage sampling signal into a digital signal stream comprises: converting the analog current signal and the analog voltage signal into a digital signal stream.

6. The method of claim 5, wherein, The inputting the current sampling signal and the voltage sampling signal into an amplification circuit model to obtain an analog current signal and an analog voltage signal comprises: determining an input amplitude of the current sampling signal and / or the voltage sampling signal; dynamically determining a target amplification multiple of the amplification circuit model based on a comparison result of the input amplitude and a preset amplitude threshold range; Adjust a gain parameter of the amplification circuit model based on the target amplification multiple, and based on the gain parameter, amplify the current sampling signal and the voltage sampling signal to obtain an analog current signal and an analog voltage signal.

7. The method of claim 6, wherein, The target amplification multiple of the amplification circuit model is dynamically determined based on a comparison result of the input amplitude and a preset amplitude threshold range, including: If the input amplitude is greater than or equal to a first amplitude threshold, a minimum gain value is taken as the target amplification multiple of the amplification circuit model; If the input amplitude is less than or equal to a second amplitude threshold, a maximum gain value is taken as the target amplification multiple of the amplification circuit model; If the input amplitude is greater than the second amplitude threshold and less than the first amplitude threshold, the target amplification multiple of the amplification circuit model is determined based on the input amplitude and the first amplitude threshold.

8. The method according to any one of claims 1-4, characterized in that, The resistance value of the sampling resistor is determined based on an equivalent circuit model of the current transformer and a preset maximum current loss error.

9. An apparatus for measuring the AC resistance of a cable, characterized by The method comprises: A signal acquisition module is configured to acquire a current sampling signal and a voltage sampling signal of a cable, wherein the current sampling signal is obtained by connecting a sampling resistor in series at a secondary side of a current transformer and measuring a voltage drop of the sampling resistor, and the voltage sampling signal is obtained by symmetrically arranging sampling points at both ends of the cable and performing double-end synchronous acquisition; An analog-to-digital conversion module is configured to convert the current sampling signal and the voltage sampling signal into a digital signal stream, wherein the digital signal stream comprises a current signal stream and a voltage signal stream; A resistance calculation module is configured to input the digital signal stream into a trapezoidal integral resistance calculation model to obtain an alternating current resistance of the cable, wherein the trapezoidal integral resistance calculation model is a model for calculating an alternating current resistance based on a current signal stream and a voltage signal stream in a digital signal stream, and is constructed based on a trapezoidal integral method.

10. An electronic device, comprising: The method comprises: A memory and a processor; The memory stores computer execution instructions; The processor executes the computer execution instructions stored in the memory, so that the processor executes the method according to any one of claims 1-8.

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